A child weighs 66.8 pounds and is ordered solu-medrol 1.6 mg/kg. The medication is labeled 500 mg/4 mL. How many milliliters should be administered, rounding to the nearest tenth?

• A. 0.4 mL
• B. 0.3 mL
• C. 0.5 mL
• D. 0.8 mL

Answer: (A)

The key idea is to convert weight to kilograms, then apply the mg/kg dose to find the total milligrams needed, and finally use the medication’s concentration to convert that dose into milliliters.

First, convert the child’s weight: 66.8 lb divided by 2.2046 equals about 30.3 kg. Multiply by the ordered dose per kilogram: 1.6 mg/kg × 30.3 kg ≈ 48.5 mg. The solution is labeled as 500 mg in 4 mL, which is a concentration of 125 mg per mL (500 mg ÷ 4 mL = 125 mg/mL). To find the volume to administer, divide the required milligrams by the concentration: 48.5 mg ÷ 125 mg/mL ≈ 0.388 mL. Rounding to the nearest tenth gives 0.4 mL. Therefore, about 0.4 mL should be given.